The products of the present invention mainly find application in feeding of young farm animals, especially young ruminants however, other animals like pets are not excluded. Young calves, lambs and pigs depend on mother's milk to provide nourishment during the period when the rumen and other digestive functions have not yet developed. Young animals are therefore unable to utilise the feed consumed by adult animals. For calves this period comprises two stages.
The first is the so-called pre-ruminant stage i.e. when the digestive functions are more akin to those of monogastric animals. During the second stage the rumen is developing but is not yet capable of fully performing the animals needs. Depending on the type of food offered and the intended use of the animals the pre-ruminant stage may be shorter or longer. Because of the high costs and inconvenience of feeding liquid cow's milk, artificial milk replacers have been developed. Milk replacers contain the following ingredients; milk proteins, fat, carbohydrates, vitamins and minerals. Milk proteins generally used are whey proteins and dried skim milk powder manufactured from cow's milk.
The physico-chemical and nutritional characteristics of the milk proteins have been shown to be of such a nature that replacement with other proteins gives rise to a lot of problems. When artificial milk replacers are made the finished feed product contains a series of components and care should be taken that the mixture has the right dispersibility, suspendibility in water, solubility and fat-binding ability. Moreover, care has to be taken that the color, taste and smell are acceptable.
The supply and costs of skimmed milk powder make it attractive to try to find other protein sources for pre-ruminant or young ruminant feed purposes. A lot of effort has been spend on trying to find or develop suitable protein sources for example, efforts have been made to develop products starting from soya bean meal, from fish meal, and from microbial sources such as yeasts. It has turned out that the finding of a suitable alternative protein source is not a straightforward process. In particular problems have occurred with the solubility and suspendibility of products, moreover inadequate growth due to the presence of anti-nutritional factors and low feed conversion has often been observed. In addition when starting from meal or flour the product normally would contain starch and fats. In order to avoid this additional processing steps are required which include degradation of the mentioned unwanted products and purification.
British patent GB 1,519,164 discloses a process for preparing a vegetable protein concentrate for use in feeding young animals which comprise acid hydrolysis of a first batch of finely ground vegetal flour, alkaline hydrolysis of a second batch of the same vegetal flour material, mixing the hydrolysates and drying the mixture.
European patent EP 0 479 596 B discloses a process for treating sources of vegetable protein and carbohydrate comprising, preparing an aqueous slurry of vegetable proteins and carbohydrates; adjusting the pH of the slurry between 3.5 and 6; pretreating the slurry with a viscosity reducing agent (an enzyme or an anti-oxidant); heating the slurry; cooling and hydrolysing with a hydrolysing agent from a source of alpha-galactosidase.
U.S. Pat. No. 5,565,225 relates to a modified soy flour/wheat feed (MSWF). Such a product is obtained by mixing soy flour and wheat flour, gelatinising the starch and reacting the mixture with an effective amount of malted grain.
U.S. Pat. No. 5,138,038 discloses protein partial degradation products obtainable from grain proteins by specific degradation treatment. The products are useful as quality improving agents for various food stuffs, as surface active agents and as dispersing agents for particles.
German patent application DE 4116744 relates to an enzymatic process for obtaining spices from soya meal or wheat proteins.
From the above references and in the general literature it appears that vegetable proteins are considered as an interesting protein source because they are cheap and available in large quantities. Among the vegetable proteins soya proteins and cereal proteins have been considered.
A major drawback of the use of high amounts of soya proteins in milk replacers is that soya contains a large amount of anti-nutritional factors which severely restricts their potential use. Recently, wheat protein has been introduced on the market for replacing milk proteins. Both soya and wheat proteins however show a limited potential for inclusion in milk replacers instead of skimmed milk powder, especially when they are used in untreated form. Addition of these proteins results in decrease of feed conversion due to inefficient protein digestion.
In an attempt to use mixtures of soya and cereal proteins it appeared that mixtures of these proteins are not physically stable and give rise to unstable suspensions. Soya protein concentrate itself also does not give good and stable suspensions in water, the protein precipitates in less than 10 minutes. A further drawback of the use of soya proteins is the large amount of anti-nutritional factors.
The present invention solves the stability problems of the protein suspensions while at the same time a considerable reduction of the anti-nutritional activity of the soya protein is observed in the young animals.